363-9 Fall to Winter Soil Nitrate Retention and Profile Distribution In Winter Wheat: Effects of Starter and Preceding Corn Nitrogen Applications.



Wednesday, October 19, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Patrick Forrestal1, Robert Kratochvil1 and John Meisinger2, (1)University of Maryland, College Park, MD
(2)BARC-East - 10300 Baltimore Ave, USDA-ARS, Beltsville, MD
Winter carryover of residual nitrate (NO3-N) can contribute to the spring nitrogen (N) requirements of winter wheat (Triticum aestivum, L.).  Nitrogen management in the preceding corn (Zea mays, L.) crop and fall starter N applied at wheat planting are potential sources of such carryover NO3-N.  This study examined the effects of preceding corn N and wheat fall starter N applications on mid- to-late winter soil NO3-N pools and NO3-N soil profile distribution.  Replicated field studies using a randomized complete block split-plot design were established at nine site years on the Maryland Coastal Plain and Piedmont regions.  Corn plots that received corn N rates (the main plot factor) of 0, 135, 202, and 269 kg ha-1 were established in the spring.  Following harvest, soil residual NO3-N to 60 cm depth was measured, and wheat was planted.  Wheat starter N rates (the split-plot factor) of 0 and 34 kg ha-1 were applied, and winter soil samples to 60 cm depth were collected to assess NO3-N retention.  Corn N fertilization was found to have a significant impact on soil NO3-N at both fall and winter sampling dates.  However, soil NO3-N levels diminished between fall and late winter, particularly at sandy textured sites.  Typically, application of 34 kg ha-1 fall starter N did not significantly increase soil NO3-N levels in the surface 60 cm.  Where significantly increased winter NO3-N was detected, it was concentrated at the deeper sampling increment (30 to 60 cm), with the surface 15 cm being NO3-N depleted at all sites.  These data indicate potential for carryover NO3-N contribution to spring wheat growth where fall soil NO3-N levels are high and winter precipitation is below average; however, fall starter N should not be applied with the expectation of a significant spring carryover benefit.
See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Nitrogen and Crop Production: II